Electrical apparatus



Oct], 1946. v BENIOFF 2,408,405

ELECTRICAL APPARATUS Filed Oct. 23; 1940 2 Sheets-Sheet 2 INVENTOR' Huyo genie/7 ATTORNEY Patented Oct. 1, 1946 UNITED STATES PATENT OFFICE 2,408,405 I I v ELECTRICAL APPARA'iUS Hugo Beniofl", La Canada, Califi, assignoiymesne assignments, to Submarine Signal Company, Boston; Mass, a corporation of Delaware I I Application October 23, 1940, Serial No. $621342 1- The" present invention relates to short wave transmitting and receiving systems particularly with spark circuits and electromagnetic waves of the order of one'meter or less. I f

Circuits of this type'offer difliculties principally because of the limitations in geometric dimensions that are necessary to keep the natural wave length of the apparatus short; It may be gen erally stated that the larger the geometrical dimensions of such a deviceare, the longer thewave length will be at the resonant frequency. It is" also essential in such devices, in order to transmit a substantial power, to provideas much storage capacity in" the condensersof the oscillating system; Such increase' in condenser capacity must, however, be" compensated by a decrease in the inductance or the" circuit in" order to maintain the freguency and wave length at' the" desired values:

In" addition to these features" it is: also neces-" sary to' provide the-correct" type of spark gap sothat' a maximum breakdown voltage may be obtained and rapid quenching may be effected. Theseie'atures work for an increased power and efficiency in the transmitting circuit. I a a Without further describing the merits of the invention, the present invention will be described in connection with the drawings below illustrat ing the same.

In the; drawings-Fig. 1} shows a vertical secti'on through the transmitting unit; Fig. 2 shows a'vertical-sectionthroughthe receiving unit; Fig. 3 shows an isometric projection of the transnutter; Fig. 4 shows-avertical section through an-' other form of the transmitter; Fig. 5 shows an isometric pro-jection of the device a section of which is shown in Fig. 4 Fig. 6 shows-the circuit diagramof the generator for the spark p tentialyFig; '7 shows in 'cross section" another form of spark generatoflFig. Sshowsan isometric projection of the device, a section of which is shown in" Fig. 7; Fig. 9 shows the apparatus of Figs: 7 and 8- as used in a radiating horn; and Fig. 10 showsithe electrical'circuit diagram for the apparatusof Figs. 7 and 8; v a

In Figs. 1, 2an'd 3 both the receiver and transrnitter are of substantially the same external shape; Thetransmitter comprises two cone elements' l and 2 which may have rounded ends as indicated at 3, and 4. These cones which are of metal are supported by mounting'elements and 6 which are of suitable insulating material. These mounting elements 5 and. 6 fit snugly in slots or groovesinthe'sides ofthe cones and space the parallel opposing bases 1 and 8 of the cone a desired distance apart. In'the center portion of 9 Claims. (01. ash-s7) an angle of approxir'nately 60.

the bases of the cone there are provided circular recesses 9 and ill with center projecting flanges H and I2 on which are mounted points [3 and [4 of tungsten or other suitable alloy or metal, these points being conicalshape and having Electrical connections from the generator for the spark potential are made tothe' cones l and 2 at convenient and desirable points. I

The receiving device; as-indicalted inFig. -2 comprises two metallic conicale ements [5' and [6 similar to the" cones l 2- except that they are joined together in a'entral section- I-T. Qtherwise the two cones have opppsdteses l8 and I9 and are provided at a point nea the outside with a hole in which there i's' screweda stud: ZVhaVin'g v a detector element 2| of silicon, g a-lenaor other sinner mater-inset arec'ess atflthe ens-or the stud. On the opposite cone Hi there mounted ina position opposite to the detectora wire 23 insulated iron i" the; cone I 6, the wire 213 being adjustable so that it nay be positioned at chosen points over the" surface of the detector element 2|. n c qr -the cope eien ents 2, s and [6 has a long' dimension of substantially a half wave length in the material at the resonant frequency of thee-seine U H by v Iii-thespar oscillator shown in the figures just ib hgl sq nw. Q o ci t n, s: Sum ciently high so thatthereds very little current penetrationinternally of the metallic structure. The capacity in the system iorfth'e storage of electrostaticfenergy is made up of the capacities between the two con-es l and 2 most otwhich is concentrated between'thei opposing surfaces 1 and" 8. [The inductanceof the system isalso dependent upon the geometric configuration of the conicar elenient sand it ma be stated that with larger conesof the" same'shape the inductance of th'e system incr'e ses accordingly. Other forms of spark oscillators shown in other figureshave a g eater capacity with the same wave length and in thesecases the geometrical configuration of theosc'illatoij havejbeen changed to increase the tr'al. circular rebess'et lportions if; and 30" having peripheral grooves inwhich a cylinder or ring- 3| o'f- Amphenoli Bakelit glass 0 1" other insiil'ating material is snugly positioned to form a chamber 32 within the ring. At the center of this chamber each conical metallic element 26 has a metallic insert 33 and 34 set therein with tungsten spark points 35 and 36 at the center thereof opposed to one another. The elements 25 and 26 may be supported and held in positions relative to each other by means of the U-shaped bracket 31 having supporting branches 3B and 39 on which the elements 26 and 25 are respectively mounted. The supporting arms 38 and 39 are made of insulating material as, for instance, Amphenol, or Bakelite, similar to that used forv the ring 3.! The conical frustum 25 and 26 may be an aluminum.

compound as, for instance, duraluminum or some other similar type of metal, if desired.

The generating circuit for generating the potential necessary to provide a train of. sparks at the desired frequency is shown in Fig. 6. In

this case a Tesla type transformer with a thyratron tube in place of spark 49 with primary 4| and high voltage secondary G2 is used, the output being across the secondary 42 to which the tank circuit may be connected.

The primary circuit is completed through one of the condensers C1, C2 or C3 and one of the resistances R1 to R5, inclusive, by proper connections of the switches 44 and 45. The condensers C1, C2 or C3 are charged by the direct current high potential source indicated at 46 the negative end of which is grounded and the positive end connected in parallel to one end of all the resistances. The condensers are discharged by means of the thyratron tube 47 the grid of which is biased by the battery 48 in series with a triggering oscillating source 49 which may be sinusoidal peaked or saw-tooth in shape or whatever form is most desirable:

The output of the secondary 42 of the Tesla coil may act as the power source 50 in Fig. 10 which, as indicated in the figure, supplies power preferably through two spark gaps and resistances 52 to the main tank circuit formed by the cones 53 and 54 at the apex of which are the pointed electrodes 55 and 56. The gaps 5| may in some cases be omitted. The type of tank circuit shown in Fig. is more completely illustratedin Figs. '7, 8 and 9. In Figs. 7 and 8 the two spark electrodes 60 and 61 are preferably constructed of tungsten or other metal or alloy with points formed in a 60? cone as acontinuation of the metallic cones 62 and 63, respectively. The cones 62 and 63 are made preferably of duraluminum or copper, silver or a plated metal, and have 'a solid angle of about 60. These'cones are each provided with cylindrical end portions 64 and 65, respectively, in which are grooves or slots 66 and 51 running diametrically across the cylindrical ends. These ends 64 and 65 are supported each by the U-shaped brackets 68 and 69 made of insulating material preferably Amphenol which was previously mentioned. Surrounding the cones 62 and 63 is the conductive shell m which is slotted lengthwise at the sides as indicated by the dotted lines II and 12 in Fig. 7 to receive the side arms I3 and 14 of the bracket 69, and 75 and 16 of the bracket 58. As each bracket 68 and 69 is held tightly to the cylinder 10 by the tight-fit of the arms l3, l4, l5 and 76 of the bracket, this construction permits the proper adjustment of the sparking points in position with respect to one another. It should I also be noted from Fig. 7 that the cylinder 10 is formed as a figure of revolution by the revolution of the half section about the vertical axis through the spark electrodes. Therefore, the vertical adjustment, as viewed in Fig. 7, of the cones 62 and 63 increases or decreases the conical gaps I? and 18.

Since in the high frequency apparatus of the present nature the currents and charges are confined to the metallic surfaces, the conical gaps H and 18 act like dielectrics of a condenser and it will be seen that for a comparatively short cone, alarge capacity is obtained between the cylindrical element I0 and the cones 62 and 63. While the theory of operation is perhaps not completely understood, this construction promotes better oscillating eificiency at very high frequencies.

. It should also be observed that the potential varies continually across the gap and in the transient phenomena of the spark discharge, the

waverapidly progresses from the spark gap electrodes 60 and 6! outward in the direction of the elements of the cone. In this Way the outward ends 19 and 8D produce radiation in the shape of a ring emanating from the ends of the gap. For this purpose the cones 62 and 63 are made one-half wave length long in the structure not in'air. The form shown in Figs. 7 and 8 is preferably used in the horn Bl of Fig. 9 in which the tank spark oscillator is positioned with the cone axis AB transversely positioned in the end of the horn. In this position the radiation from the tank circuit will be in'the direction of the axis of the horn indicated by the line CD.

Having now described my invention, I claim:

1. A short wave spark tank circuit oscillator comprising a pair of metallic cones having aligned axes and arranged with the points facing each other, conductive means having a surface surrounding the conical surface of said cones opposed and spaced near thereto and insulating means supporting said cones and said means.

2. A short wave spark tank circuit oscillator comprising a pair of metallic cones of approximately 60 solid angle and arranged with the points thereof facing each other, conductive means surrounding said cones forming an airg'ap betwe'enthe surfaces of said means and said cones and means insulating said cones from each other and said conductive means.

3. A short wave spark resonant tank circuit oscillator. comprising means forming a pair of opposed metallic surfaces providing capacity for said resonant circuit having a pair of opposing electrodes projecting centrally from said surfaces, one from each'surface, the inductance of the metallic path around the surfaces with the projecting electrodes as the center and said capacity providing the tuning and resonant frequency of the oscillator, and means insulating said me tallic surfaces from each other.

4. A shortwave spark'resonant tank circuit oscillator comprising means forming apair. of opposed metallic surfaces providing capacity for said resonant circuit having a pair of opposing spark electrodes projecting centrally from said surfaces, one from each surface, the inductance of the metallic path around the surfaces with the projecting electrodes as the center and said capacity providing the tuning and resonant frequency of the oscillator, means insulating, said metallic surfaces from each other, andv means forming a chamber enclosing said spark electrodes.

5. A short wave spark resonant tank circuit oscillator comprising means forming a pairof opposed metallic surfaces providing capacity for said resonant circuit having a pair of opposing spark electrodes projecting centrally from said surfaces, one from each surface, the inductance of the metallic path around the surfaces with the projecting electrodes as the center and said capacity providing the tuning and resonant frequency of the oscillator, means insulating said metallic surfaces from each other, and means forming a chamber enclosing said spark elec-i trodes, said chamber being partially exhausted of air,

'7. A short wave spark resonant tank circuit oscillator comprising means forming a pair of opposed metallic surfaces providing capacity for said resonant circuit having a pair of opposing spark electrodes projecting centrally from said surfaces, one from each surface, the inductance of the metallic path around the surfaces with the projecting electrodes as the center and said capacity providing the tuning and resonant frequency of the oscillator, means insulating said metallic surfaces from each other, and means forming a chamber enclosing said spark electrodes, said chamber being filled with oil.

8. A short wave spark resonant tank circuit oscillator comprising means forming a pair of opposed metallic surfaces providing capacity for said resonant circuit having a pair of opposing spark electrodes projecting centrally from said surfaces, one from each surface, the inductance of the metallic path around the surfaces with the 1 projecting electrodes as the center and said capacity providing the tuning and resonant frequency of the oscillator, and means insulating said metallic surfaces from each other, said means forming said opposed metallic surfaces having an axis of symmetry of substantially a half wave length at the frequency to be transmitted or received.

9. A short wave spark tank circuit oscillator comprising a pair of metallic surfaces of revolution having aligned axes and arranged within small ends facing each other having spark electrodes at their apices, conductive means having a surface surrounding the surfaces of revolution opposed and spaced near thereto and insulating means supporting said surfaces and said means in said opposed and spaced relation to each other. HUGO BENIOFF. 

